Google has confirmed that it has gone to the US State Department, including other parties, to voice its concerns on the filter.

"Google is deeply concerned by Australia's plans to introduce a widely scoped, mandatory ISP filtering regime. We have voiced our concerns publicly and with many groups including the US State Department," Google spokesperson Lucinda Barlow told ZDNet.com.au today.

In general, censorship has not sat well with the company, which shut down its search engine in China recently after a series of cyber attacks and complaints about censorship. It diverted its Chinese search queries to the Hong Kong Google site.

The US may listen carefully to Google's concerns, given that the US Ambassador Jeff Bleich confirmed last week that the US had been in an "ongoing conversation" with Australia over the filter. The internet had to be free, he said.

"It needs to be free the way we have said skies have to be free, outer space has to be free, the polar caps have to be free, the oceans have to be free. They have to be shared. They're shared resources of all of the people of the world," he said.